Bulusan volcano erupts, triggers pyroclastic flow and ashfall in Sorsogon Province, Philippines
A phreatic eruption occurred at Bulusan volcano, Philippines, on April 28, 2025, generating a 4.5 km (1 650 feet) high ash plume and resulting in ashfall over nearby communities. The Philippine Institute of Volcanology and Seismology raised the Alert Level to 1.
Image credit: Sorsogon PIO
A phreatic eruption lasting approximately 24 minutes started at Bulusan volcano in Sorsogon Province, Philippines, at 04:36 local time on April 28 (20:36 UTC, April 27).
The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported that the event generated a voluminous bent plume reaching an altitude of 4.5 km (1 650 feet) above the crater, drifting west to southwest.
Ashfall was reported in Barangays Cogon and Bolos in Irosin, Barangays Puting Sapa, Guruyan, and Buraburan in Juban, and Barangay Tulatula Sur in Magallanes.
In addition to ashfall, a pyroclastic density current, locally known as “uson,” traveled approximately 3 km (1.8 miles) down the southwestern slopes of the volcano.
IP Camera footage of the 04:36 AM eruption of Bulusan Volcano taken by the Irosin Caldera Observation Station (VBIC) southwest of the edifice. pic.twitter.com/smGxm0LX7u
— PHIVOLCS-DOST (@phivolcs_dost) April 28, 2025
Filipinler'de #Bulusan Yanardağı patlaması yerel halkı, şafak vakti bu manzarayla karşı karşıya bıraktı. pic.twitter.com/77qHfkVeXM
— Mustafa Kılıç (@Mkilic76) April 28, 2025
PANOORIN: Ibinahagi ng Office of Civil Defense (OCD) ang ‘ashfall’ na dulot ng pagsabog ng Bulkang #Bulusan sa lalawigan ng Sorsogon ngayong Lunes, Abril 28. | via Office of Civil Defense (Video courtesy of Dong Mendoza) pic.twitter.com/EPiYepvxot
— PTVph (@PTVph) April 28, 2025
Prior to the eruption, PHIVOLCS recorded 53 volcanic earthquakes over a 24-hour observation period. Rumbling sounds were reported by local government officials approximately 15 minutes before the eruption and were recorded by infrasound sensors.
In response, PHIVOLCS raised the alert status for Bulusan from Alert Level 0 to Alert Level 1. This alert level indicates low-level unrest with the potential for additional phreatic eruptions.
PHIVOLCS maintains a strict no-entry policy within a 4 km (2.5 miles) radius of the summit, alongside a 2 km (1.2 miles) Extended Danger Zone on the southeast sector due to potential hazards, including sudden phreatic eruptions and sediment-laden stream flows.
Residents and visitors are advised to take precautions against ashfall and to remain vigilant for potential lahars, especially during periods of heavy rainfall.
Bulusan is a stratovolcano located in the Bicol region of the Philippines. It is known for its sudden, short-lived phreatic eruptions, driven by the explosive interaction of water with hot volcanic material without new magma emission.
References:
1 Bulusan volcano – Alert Level Bulletin – PHIVOLCS – April 28, 2025
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